1. Technical Field
The present invention relates to a plurality of types of control units which output control signals to electrical components to be mounted on a vehicle, to an inspection device for testing operation of the control unit before shipment, and to an inspection method.
2. Related Art
An automobile or a like vehicle is equipped with a control unit for controlling corresponding electrical components on the basis of the operating status of switches to be used for activating the various electrical components installed in the automobile. A control element having a predetermined control program installed therein beforehand is mounted on a board of the control unit. Further, the control unit is equipped with a plurality of input and output terminals. In response to a signal input to each input terminal, a predetermined control signal is output from an output terminal.
Related-art inspection means for such electrical components have performed the following operation in order to inspect whether or not an input perception function, an internal ROM checking function, and an output function of the control unit operate as designed without involvement of connection failures or a breakdown in a control element. Specifically, there is performed an operation of actually inputting, to each input terminal, a signal identical with a signal input at the time of a normal control operation (i.e., a dummy input signal) and of ascertaining a signal output from each output terminal in response to the input signal.
FIGS. 1 through 3 show the related art configurations of a plurality of types of control unit inspection devices. In each of the configurations, a custom-designed inspection machine is connected to each type of control unit.
As an example model of control unit to become an object of inspection, FIG. 1 shows a control unit 30a. The control unit 30a controls locking/unlocking action of a door lock, ascending/descending action of a power window, and a dome lamp. Moreover, FIG. 2 shows a control unit 30b for controlling right and left turn signals and a dome lamp; and FIG. 3 shows a control unit 30c for controlling a wiper motor, a washer motor, and a dome lamp.
The control unit 30a shown in FIG. 1 for controlling opening/closing action of the door lock, ascending/descending action of the power window, and the dome lamp has input/output terminals provided in Table 1.
The control unit 30b shown in FIG. 2 for controlling the right/left turn signals and the dome lamp has input/output terminals provided in Table 2.
The control unit 30c shown in FIG. 3 for controlling the wiper motor, the washer motor, and the dome lamp has input/output terminals provided in Table 3.
The control unit has a built-in control circuit. The control circuit produces a predetermined output signal in response to the dummy input signal and outputs the signal, to thereby control each type of electrical component. Of control operations, specific examples of time control performed by a timer will now be described.
(1) A room lamp illumination signal is output from a room lamp terminal for 15 seconds from the time of activation of the signal input to the door switch input terminal (i.e., for 15 seconds from when a door is opened).
(2) From a point in time when the signal input to a switch input terminal of the intermittent wiper is activated, an intermittent wiper motor drive signal is output from an intermittent wiper motor output terminal at intervals of 12 seconds.
(3) A room lamp illumination signal is output from a room lamp terminal for 15 seconds from the time of activation of a signal input to a switch input terminal of the door lock (i.e., for 15 seconds from when the door is locked).
[Problem to be Solved]
Under circumstances where a signal output from a certain specific control unit is inspected through use of the vehicle-mounted control unit inspection apparatus described above, if a signal to be input to the input terminal must be produced by combination of complicated switch logic circuits, the switch logic circuits are actually produced. By means of providing the inspection apparatus with the switch logic circuits, a signal is input to the control unit. Therefore, there has been a necessity for limiting each inspection apparatus to inspection of a specific one type of control unit.
However, a plurality of types of control units are used. If a custom-designed inspection apparatus is installed for each type of control unit, there arises a problem of an increase in inspection costs associated with an increase in the number of pieces of inspection apparatus. Further, if specific control units are manufactured in small number, there arises a problem of an increase in xe2x80x9cidle timexe2x80x9d during which the inspection apparatus for the control unit is not used.
The present invention aims at enabling a single inspection apparatus to inspect a plurality of types of control units without use of an inspection apparatus specifically designed for each type of control unit.
[Means for Solving the Problem]
The present invention provides a control unit which is provided in a vehicle, such as an automobile, and outputs a control signal to a corresponding vehicle-mounted electrical component upon being subjected to a user""s switching action, the unit comprising: input terminals for receiving control switch signals; output terminals for outputting control signals to respective electrical components; an inspection program having set therein procedures for inspecting the control unit; and an inspection program storage section for storing the inspection program.
By means of the foregoing configuration, an inspection program to be used for inspecting a control unit is stored in a control unit. At the time of inspection of the control unit, the only requirement is that the inspection program be invoked. There is no necessity of preparing an inspection apparatus corresponding to each type of control unit. More specifically, a plurality of types of control units can be inspected through use of a common inspection apparatus.
When a control unit according to the present invention is inspected by means of a time characteristic for normal use (i.e., in a normal control mode), an inspection result is not obtained until output of a signal is completed in the case of a circuit, such as a time control circuit constituted of a timer, which involves a long time interval from when a signal is input until a response signal is output or a long time interval at which a control signal is to be output. This results in an increase in the time required for inspection.
Preferably, the control unit further comprises two types of control modes; that is, a normal control mode in which the control unit performs operation for normal use after having been shipped and mounted on a vehicle, and an inspection mode in which an output signal is output from an output terminal in response to a signal input to an input terminal prior to shipping of the control unit, with a response time shorter than that in the normal control mode. In a normal control mode, the control unit performs a normal control operation, which is to be performed when the control unit is mounted on a vehicle. In the inspection mode, a signal is output, by means of shortening, from that in the normal control mode, the lighting time of a dome light or an interval at which an intermittent wiper motor drive signal is to be output, thereby enabling diminishment of a required inspection time.
Preferably, the control unit further comprises control mode switching means which switches a control mode from the normal control mode to an inspection mode only when a specific input instruction signal is input to a certain input terminal of the input terminals by means of an input method which would not be employed under normal control operation. According to the invention, only a specific input instruction signal is input to a certain input terminal of the input terminals by means of an input method which would not be employed under normal control operation. As a result, the input terminal to be used in a normal control mode can be used also as an input terminal for a control mode switching instruction signal.
An inspection apparatus according to the present invention involves a necessity of running a custom-designed inspection program for each type of control unit to be inspected. The present invention provides a control unit inspection system including a control unit and an inspection apparatus for inspecting the control unit, the system further comprising communications means which, upon receipt of an instruction from the inspection apparatus, transfers a custom-designed inspection program stored in the inspection program storage section provided on each control unit to the inspection apparatus from a specific terminal of the output terminals. As a result, modifications to the inspection program to be run by the inspection apparatus are facilitated.
According to the present invention, the control unit cannot directly run the inspection program stored therein; rather, the inspection program is transferred to the inspection apparatus, where the program must be implemented. The communications means temporarily uses specific input/output terminals of the control unit as input/output terminals for serial communication, thereby enabling transfer of the inspection program stored in the control unit to the inspection apparatus.
The present invention provides an inspection apparatus, wherein an inspection apparatus control section for centralizing inspection procedures has a rewritable inspection program storage section for reading and storing an inspection program which is an inspection procedure specifically designed for each type of control unit and is stored in the control unit. According to the present invention, the inspection program stored in each control unit is transferred to the inspection apparatus by means of the communications means. The inspection program is then stored in the rewritable inspection program storage section provided in the inspection apparatus control section. An inspection program corresponding to the control unit can be implemented, and an inspection program to be implemented by the inspection apparatus can be readily modified.
Preferably, the inspection apparatus control section has model identification means for acquiring information required for specifying the model of a control unit by means of the inspection program transferred by the communications means. According to the present invention, information required for specifying the model of a control unit is retained in the inspection program stored in the inspection program storage section in the control unit. When the inspection program has been transferred to the inspection apparatus, the model of the next control unit to be inspected by the inspection apparatus can be identified.
Preferably, the control unit inspection apparatus further comprises input devices for enabling conduction of a dummy input inspection signal from the input terminal for each type of control unit at the time of inspection of a control unit, and the inspection apparatus control section has input means for controlling the respective input terminals in the inspection apparatus. According to the present invention, each type of control unit has a plurality of input terminals. At the time of inspection of the control unit, the inspection apparatus is provided with input devices which are connected to all input terminals and can control conduction of the respective input terminals. Further, the input devices can be controlled freely, by means of the input means provided in the inspection apparatus control section, thereby enabling input of a dummy input inspection signal.
Preferably, the inspection apparatus control section is provided with a custom-designed input device for each type of control unit to become an object of inspection. The inspection apparatus control section further comprises input device changeover means for switching an input device in accordance with the type of a control unit when a change has arisen in the model of the control unit to be inspected. According to the present invention, the number of input terminals changes in accordance with the type of a control unit. Hence, custom-designed input means constituted of a plurality of switching circuits is prepared for each type of control unit. Every time a change arises in the model of an object of inspection, the input means can be switched.
Preferably, the inspection apparatus further comprises a dummy load storage section having stored therein a plurality of dummy loads which at the time of an operation test receive a signal output from the control unit instead of having each type of electrical component. According to the invention, each type of control unit has a plurality of output terminals. The inspection apparatus has, for each output terminal, an individual dummy load which serves as a substitute for an electrical component to be connected to the control unit when the control unit is mounted on a vehicle, thereby reproducing the same operating situation as that effected when the control unit is mounted on a vehicle. Accordingly, a control operation to be performed by a control unit can be inspected.
Preferably, the inspection apparatus has a custom-designed dummy load storage section provided for each type of control unit to be inspected. Moreover, the inspection apparatus control section has dummy load changeover means for switching a dummy load storage section to be used in accordance with the type of a control unit to be inspected. According to the invention, even when the number of output terminals of an object of control changes according to the model of control unit, a control unit of different type can be inspected, by means of merely preparing a dummy load storage section constituted of a plurality of load circuits, and switching a dummy load storage section to be used every time the model of an object of inspection changes.
The present invention also provides a method of inspecting the control unit inspection device set forth, the method comprising the steps of: storing, into an inspection program storage section provided in each control unit, an inspection program for which custom-designed inspection procedures are set for each type of control unit; transferring, by means of communication means, the inspection program to a rewritable inspection program provided in an inspection apparatus; automatically identifying the model of control units supplied in an arbitrary sequence, by means of causing the inspection apparatus to run the inspection program; and inspecting a plurality of types of control units through use of a single inspection apparatus. According to the present invention, a program for inspecting a control unit is stored in a control unit. Even when control units of different types are supplied to the inspection apparatus in any possible sequence, a single inspection apparatus can inspect the control units appropriately.